The Division of Blood Diseases and Resources (DBDR) proposes to support, through research contracts, the refinement of nucleic acid-based assays to identify infection of blood and organ/tissue donors by blood-borne viruses, most notably human immunodeficiency virus (HIV) and hepatitis C virus (HCV). The major objectives of this program are: 1) to refine for use in clinical laboratories, blood bank laboratories or both, one or more nucleic-acid based techniques that will be feasible for the direct detection of blood-borne viruses in donors of organs for transplantation and/or of blood for transfusion to reduce the antibody-negative window period between infectivity and detection to the shortest possible time and, when possible, obviate the need for indirect antibody tests; and 2) to file for investigational new drug exemption (INDs) with the Food and Drug Administration (FDA), and submit and obtain approval for product license applications (PLAs). The major focus for this research is the earliest detection of infection by HIV. Currently, the enzyme immunoassays employed by blood banks for the detection of HIV antibodies are required to detect the presence of HIV-1 and HIV-2 antibodies; these tests have been shown to detect many but not all antibodies to HIV-0. Hence, another important goal of this procurement is to obtain a nucleic acid-based assay capable of detecting HIV-1, HIV-2 and HIV-0. The assay should also have the flexibility to be readily adaptable to the detection of variants of HIV that may be described in the future. In addition, because of its clinical importance, HCV must also be detected in a similar system. To improve practicability, the detection of more than one agent per test (multiplex system) is an important goal. The two highest priority viruses to be detected, HIV and HCV, may or may not lend themselves to multiplexing together. The testing method (s) envisioned must be able to detect each of these viruses, alone or in multiplexing format, but earlier availability of an individual test is more important than a later availability of multiplexed tests.